Compatible with Leupold post-2004 riflescopes with 20mm Objective lenses and 1" Maintubes. Designed for Leupold scopes built after 2004, Alumina Flip-Back lens covers feature powerful neodymium magnets to hold them securely closed and the triple O-ring seals provide maximum protection from the elements. Constructed out of durable 6061-T6 aircraft grade aluminum, they are precisely machined to allow for quick and easy operation, and a low-profile position, when open, make these Flip-Back lens covers stand above the rest. The round objective and ocular models can be rotated so they can open in any direction. Many Leupold scopes built prior to 2004 can be threaded to accept Alumina accessories.